diff --git a/rust2rpm/conf.py b/rust2rpm/conf.py
index fbf93e7..9b7b299 100644
--- a/rust2rpm/conf.py
+++ b/rust2rpm/conf.py
@@ -2,7 +2,7 @@ import configparser
 import os
 import sys
 import tomllib
-from typing import Optional
+from typing import Any, Optional
 
 import jsonschema
 
@@ -258,17 +258,17 @@ class IniConf:
         if lib_requires := merged.get("lib.requires"):
             if "lib_requires" not in settings.keys():
                 settings["lib_requires"] = dict()
-            settings["lib_requires"][None] = to_list(lib_requires)
+            settings["lib_requires"][None] = to_list(lib_requires)  # type: ignore
 
         for feature in features:
             if lib_feature_requires := merged.get(f"lib+{feature}.requires"):
                 if "lib_requires" not in settings.keys():
                     settings["lib_requires"] = dict()
-                settings["lib_requires"][feature] = to_list(lib_feature_requires)
+                settings["lib_requires"][feature] = to_list(lib_feature_requires)  # type: ignore
 
         settings["conf_file"] = len(confs) == 1
 
-        return IniConf(**settings)
+        return IniConf(**settings)  # type: ignore
 
 
 class TomlConf:
@@ -292,16 +292,22 @@ class TomlConf:
     def package_summary(self) -> Optional[str]:
         if package := self._package:
             return package.get("summary")
+        else:
+            return None
 
     @property
     def package_description(self) -> Optional[str]:
         if package := self._package:
             return package.get("description")
+        else:
+            return None
 
     @property
     def package_supported_arches(self) -> Optional[list[str]]:
         if package := self._package:
             return package.get("supported-arches")
+        else:
+            return None
 
     @property
     def _features(self) -> Optional[dict]:
@@ -311,16 +317,22 @@ class TomlConf:
     def features_enable_all(self) -> Optional[bool]:
         if features := self._features:
             return features.get("enable-all")
+        else:
+            return None
 
     @property
     def features_enable(self) -> Optional[list[str]]:
         if features := self._features:
             return features.get("enable")
+        else:
+            return None
 
     @property
     def features_hide(self) -> Optional[list[str]]:
         if features := self._features:
             return features.get("hide")
+        else:
+            return None
 
     @property
     def _requires(self) -> Optional[dict]:
@@ -330,26 +342,36 @@ class TomlConf:
     def requires_build(self) -> Optional[list[str]]:
         if requires := self._requires:
             return requires.get("build")
+        else:
+            return None
 
     @property
     def requires_test(self) -> Optional[list[str]]:
         if requires := self._requires:
             return requires.get("test")
+        else:
+            return None
 
     @property
     def requires_lib(self) -> Optional[list[str]]:
         if requires := self._requires:
             return requires.get("lib")
+        else:
+            return None
 
     @property
     def requires_bin(self) -> Optional[list[str]]:
         if requires := self._requires:
             return requires.get("bin")
+        else:
+            return None
 
     @property
     def requires_features(self) -> Optional[dict[str, list[str]]]:
         if requires := self._requires:
             return requires.get("features")
+        else:
+            return None
 
     @staticmethod
     def load(path: str, features: set[str]) -> "TomlConf":
@@ -374,9 +396,9 @@ class TomlConf:
 
     @staticmethod
     def from_conf(conf: IniConf) -> "TomlConf":
-        settings = dict()
+        settings: dict[str, Any] = dict()
 
-        package = dict()
+        package: dict[str, Any] = dict()
         if conf.summary:
             package["summary"] = conf.summary
         if conf.supported_arches:
@@ -384,7 +406,7 @@ class TomlConf:
         if package:
             settings["package"] = package
 
-        features = dict()
+        features: dict[str, Any] = dict()
         if conf.all_features is not None:
             features["enable-all"] = conf.all_features
         if conf.enabled_features:
@@ -394,7 +416,7 @@ class TomlConf:
         if features:
             settings["features"] = features
 
-        requires = dict()
+        requires: dict[str, Any] = dict()
         if conf.buildrequires:
             requires["build"] = conf.buildrequires
         if conf.testrequires:
diff --git a/rust2rpm/crate.py b/rust2rpm/crate.py
index 44ec7b1..dfefd4d 100644
--- a/rust2rpm/crate.py
+++ b/rust2rpm/crate.py
@@ -180,7 +180,7 @@ def process_project_local(
         name, version = guess_local_project_version_from_path(project)
 
         log.warn(f"Falling back to {name!r} as the name of the project (based on the name of the containing folder).")
-        diffs = (None, None)
+        diffs: tuple[Optional[list[str]], Optional[list[str]]] = (None, None)
 
     else:
         package = metadata.packages[0]
@@ -211,7 +211,7 @@ def resolve_version(crate: str, version: str) -> Optional[str]:
         log.info("Resolving partial version ...")
 
         available_versions = query_available_versions(crate)
-        resolved_version = max(filter(lambda x: x in parsed_version, available_versions), default=None)
+        resolved_version = max(filter(lambda x: x in parsed_version, available_versions), default=None)  # type: ignore
 
         if resolved_version is None:
             log.warn("Partial version does not match any available version.")
diff --git a/rust2rpm/generator.py b/rust2rpm/generator.py
index b2b6848..ff83f21 100644
--- a/rust2rpm/generator.py
+++ b/rust2rpm/generator.py
@@ -490,9 +490,9 @@ def spec_render_workspace(
     else:
         cargo_args = ""
 
-    license_strs = {package.license for package in metadata.packages if package.license}
+    license_strs = list({package.license for package in metadata.packages if package.license})
     if len(license_strs) == 1:
-        rpm_license_tag, rpm_license_comments = translate_license(target, list(license_strs)[0])
+        rpm_license_tag, rpm_license_comments = translate_license(target, license_strs[0])
     else:
         is_composite = (
             lambda x: (" " in x and " WITH " not in x and "(" not in x and ")" not in x) or "(" in x or ")" in x
diff --git a/tox.ini b/tox.ini
index ee686d7..f8562ae 100644
--- a/tox.ini
+++ b/tox.ini
@@ -33,6 +33,7 @@ setenv =
 deps =
     mypy
     pytest
+    types-jsonschema
     types-requests
     types-tqdm
     -rrequirements.txt